Container closure seaming method and apparatus



H. WYSS Dec. 17, 1968 CONTAINER CLOSURE SEAMING METHOD AND APPARATUSFiled Feb. 6, 1967 United States Patent Oflice Patented Dec. 17, 19683,416,476 CONTAINER CLOSURE SEAMING METHOD AND APPARATUS Hans Wyss,Corsier, Vaud, Switzerland, assignor to Afico S.A., Lausanne,Switzerland, a corporation of Switzerland Filed Feb. 6, 1967, Ser. No.615,296 Claims priority, application Switzerland, Feb. 11, 1966,

13 Claims. (11. 113-30 ABSTRACT OF THE DISCLOSURE The invention relatesto the seaming of and end closure with a curled rim to a can body withan outwardly turned lip by a novel method comprising the steps ofpinching the rim around the lip, then turning the pinched rim obliquelyand downwardly and finally, pressing the rim against the side wall ofthe can body. The invention also relates to an apparatus for carryingout this method by means of a mandrel provided with a shoulder, a springloaded roller, a frusto-conical roller and a flattening cylindricalroller. The invention relates further to a can made by the said seamingmethod.

This invention relates to container closures, more particularly to theseaming of an end closure with curled rim on a tin can body with anoutwardly turned lip.

According to the known seaming process generally utilised the can bodyhas a lip turned outwardly at right angles to the body wall and the endclosure a curled rim.

The curled rim facilitates stacking and easy separation of the endclosures, since they do not have the tendency to wedge together.

During the first operation of the known process, the curled rim isrolled over the lip of the can body, which may be called a roll seam.This rolling is effected by means of a specially profiled roller.

The second and last operation consists of flattening and pressing therolled rim against the wall of the can body.

Unfortunately, by this method, the hooks formed by the lip and rim donot overlap completely. Consequently, the resulting seal may provedefective in that the can is not airtight, chiefly, for example, at theintersection of the rim and the longitudinal seam of the can body. Atthis place the conditions of seaming prove more diflicult due to thedouble thickness of the tinplate of the can body. In order to ensuresatisfactory air tightness, it is necessary to provide relatively largeseams which requires a larger tinplate surface.

Furthermore, since the rolling of tinplate during the first operation ismade without support, its success will depend chiefly on the correctsetting of the machine (profile and pressure of the roller) and on thethickness and rigidity of the tinplate as well as the diameter of thecan.

Experience has shown that the roll seam is practically inapplicable tothin tinplate, particularly when the diameter of the can is small. Thisthin tinplate, generally much harder, has a tendency to form wrinklesthus jeopardizing the air-tightness of the seam. The reduced thicknessof the tinplate is however an important economic factor, primarily inthe manufacture of small cans.

The process according to the present invention overcomes the drawbacksdescribed above.

The present invention provides a novel method for seaming an end closurewith a curled rim to a can body having a side wall terminating in anoutwardly turned lip, said end closure comprising a downwardly embossedcentre portion and an upwardly turned wall portion flaring outwardlyfrom the periphery of said centre portion and terminating in adownwardly curled rim, said method comprising the steps of pinching saidcurled rim around said lip, by pressing said rim against a projectingportion of holding'means overlapping said curled rim, said holding meanscomprising a central portion adapted to engage and support the side wallof the closure during the seaming, then turning the pinched rimobliquely and downwardly and finally, pressing the obliquely downturnedpinched rim against the side wall of the can body.

The invention also relates to an apparatus for seaming an end closure toa can body having a side wall terminating in an outwardly turned lip,said end closure comprising a downwardly embossed centre portion and anupwardly turned wall portion flaring outwardly from the periphery ofsaid centre portion and terminating in a downwardly curled rim, saidapapratus comprising holding means adapted to position the curled rim ofthe closure over the lip of the can body, said holding means comprisinga central portion adapted to engage and support the side wall of theclosure during the seaming and a projecting portion overlapping thecurled rim of the closure, pinching means adapted to pinch said curledrim around said lip by pressing said rim against the projecting portionof the holding means, means for turning the pinched rim obliquely anddownwardly and means for pressing the obliquely downturned pinched rimagainst the side wall of the can body.

The invention also provides a can, particularly made out of thintinplate, obtained by the above seaming method.

FIGURES 1 to 4, which are partial sections through the seam, illustratethe different stages of the operation according to the invention.

FIGURESS to 7 illustrate diagrammatically various embodiments of theapparatus according to the invention.

The seaming of the end closure 2 with a curled rim (FIG. 1) is effectedon a can body 1 having a lip turned outwardly at right angles to thebody wall.

During the first operation (FIG. 2), the end closure rests on a mandrel3 having a shoulder and said end closure is supported on two of itsfaces on said mandrel. The downwardly embossed centre portion issupported namely on the slightly conical side of the mandrel and theflatter part of the rim which covers the lip of the can body issupported by the projecting portion of the mandrel. The periphery of therim is closed around the outwardly turned lip of the body by pinching itbetween the projecting portion of the mandrel 3 and a roller 4 ofgenerally cylindrical form. This roller may slide axially on the shaft 5supported by the seaming head of a machine of known type and is pressedagainst the projecting portion of the mandrel by a spring 6.

By moving this roller around relative to the can body, the rim of theend closure is compressed in such a way as to eliminate progressivelyany wrinkling which may form therein, the projecting portion of themandrel being used as a support during this operation.

The second operation consists of turning the pinched rim downwardlythrough an angle of about 45, by means of a frusto-conical roller 7turning round the can body (FIG. 3).

Finally, the third operation consists of pressing and flattening thepinched rim against the side wall of the can body whilst it is supportedby the side of the mandrel. This operation is effected by means of anessentially cylindrical roller having a groove with approximately theprofile of the seam and turning round the can body (FIG. 4).

The method according to the present invention, compared to the knownmethod, has the following advantages:

(1) The hooks formed by the lip and rim overlap completely, giving atighter seam. Hence the defects encountered mainly at the intersectionof the rim and the longitudinal seam of the can body are practicallyeliminated.

(2) It is possible to use thin tinplate for the manufacture of smalldiameter cans (73 mm. or less) since the risk of wrinkling ispractically non-existent.

(3) All things being equal, the air-tightness is improved so that it istherefore possible to reduce the depth (h) of the seam.

(4) Since the first operation is carried out against the solid supportprovided by the projecting portion of the mandrel, any possibledeformations may be controlled more precisely and hence the seam will bemore compact.

(5) The total time of the operation is reduced, in that the process isaccomplished during a cycle comprising a smaller number of revolutionsof the seaming head or of the can, as will be shown further on.

This process may be applied when the seaming head rotates with respectto the can body, and also when the can body rotates and the seamingrollers remain stationary.

According to one preferred embodiment of the invention, the apparatuscomprises 4 seaming rollers symmetrically disposed with respect to theaxis of the mandrel (M) spaced at 90 intervals from each other asillustrated in FIG. 5, the rollers being supported by a rotatableseaming head.

The number of revolutions needed for the seaming head to carry out theprocess is 4% revolutions, which cycle may be divided as follows:

2 revolutions for the first operation (FIG. 2) with 2 seaming rollers m1 /6 revolutions for the second operation (FIG. 3) with the seamingroller m 2. /6 revolutions for the third operation (FIG. 4) with theseaming roller m 5 /3 revolutions (relative angular displacement ofrollers) If the second operation overlaps the first by /6 and the thirdoverlaps the second by 71 revolution, the total effective angulardisplacement is reduced to 4% revolutions. It should be noted that thesecond operation is to be effected very rapidly, since this is one ofthe elements of success, otherwise the pinched rim might open.

In comparison, the cycle of the known process effected with a currentseaming machine having 4 rollers also disposed as shown in FIG. 5, maybe divided as follows:

4 revolutions for the first operation with 2 rollers m 2% revolutionsfor second operation with 2 rollers m and m 6% revolutions (relativeangular displacement of the rollers) From this total an overlap of halfa revolution should be subtracted between the two operations, since eachone is eflected by 2 seaming rollers spaced at 180 from each other,hence the effective angular displacement is 6% revolutions.

According to another embodiment, the apparatus comprises a roller foreach operation i.e. 3 rollers m disposed around the mandrel M as shownin FIG. 6. If an overlap of of a revolution between each operation istaken into account, the effective angular displacement of the seaminghead is 5 /2 revolutions with 3 /2 turns instead of 2 for the firstoperation.

According to yet another embodiment where contrary to the precedingexamples, the mandrel M and the can body rotate relative to thestationary seaming rollers,

the 3 rollers may be arranged as illustrated by FIG. 7 instead of beingarranged at 120 intervals. In comparison to the preceding embodiment,this arrangement allows for a greater overlap between the operations;bringing them to revolution, the total angular displacement of the canis 5 /6 revolutions.

It is understood that the above embodiments have been described andillustrated only by way of example and that minor modifications may bemade without departing from the scope of the invention.

I claim:

1. A method for seaming an end closure to a cam body having a side wallterminating in an outwardly turned lip, said end closure comprising adownwardly embossed centre portion and an upwardly turned wall portionflaring outwardly from the periphery of said centre portion andterminating in a downwardly curled rim, said method-comprising the stepsof pinching said curled rim around said lip, by pressing said rimagainst a projecting portion of holding means overlapping said curledrim, said holding means comprising a central portion adapted to engageand support the side wall of the closure during the seaming, thenturning the pinched rim obliquely and downwardly and finally, pressingthe obliquely downturned pinched rim against the side wall of the canbody.

2. A method according to claim 1, in which the can and end closure turn4% revolutions relatively to seaming rollers symmetrically disposed withrespect to the axis of said holding means,

3. A method according to claim 1, in which the can and end closure turn5 /6 revolutions relatively to three stationary seaming rollers groupedclose together.

4. An apparatus for seaming an end closure to a can body having a sidewall terminating in an outwardly turned lip, said end closure comprisinga downwardly embossed centre portion and an upwardly turned wall portionflaring outwardly from the periphery of said centre portion andterminating in a downwardly curled rim, said apparatus comprisingholding means adapted to position the curled rim of the closure over thelip of the can body, said holding means comprising a central portionadapted to engage and support the side wall of the closure during theseaming and a projecting portion overlapping the curled rim of theclosure, pinching means adapted to pinch said curled rim around said lipby pressing said rim against the projecting portion of the holdingmeans, means for turning the pinched rim obliquely and downwardly andmeans for pressing the obliquely downturned pinched rim against the sidewall of the can body.

5. An apparatus according to claim 4, in which said holding means is amandrel provided with a shoulder.

6. An apparatus according to claim 4, in which the height of theshoulder of the mandrel is at least equal to the depth of the seam.

7. An apparatus according to claim. 4, comprising 4 seaming rollerssymmetrically disposed about the axis of said holding means, saidrollers being supported by a rotatable seaming head.

'8. An apparatus according to claim 7, comprising two spring-loadedpinching rollers, one frusto-oonical roller and one substantiallycylindrical flattening roller.

9. An apparatus according to claim 4, comprising rotatable holding meansand 4 stationary seaming rollers spaced at intervals around said holdingmeans.

10. An apparatus according to claim 4, comprising 3 seaming rollersspaced at intervals from each other and being supported by a rotatableseaming head.

11. An apparatus according to claim 4, comprising rotatable holdingmeans and 3 stationary seaming rollers at 120 from each other.

12. An apparatus according to claim 4, comprising rotatable holdingmeans and 3 stationary seaming rollers grouped close together.

5 6 13. A can, particularly made out of thin tinplate, ob- 2,455,73712/1948 Coyle 113-120 tained by the method of claim 1. 2,643,627 6/ 1953Wobbe 113-120 References Cited CHARLES W. LANHAM, Primary Examiner.UNITED STATES PATENTS 5 RONALD D. GREFE, Assistant Examiner.

2,196,206 4/1940 Foss 113-420 US. Cl. X.R.

2,337,452 12/1943 COmpo 113-30 113-1, 121

